Purpose: To report additional endpoints, including 2-year primary patency, patient outcomes, and safety results, as well as the initial assessment of hypoechogenic halo from the IMPERIAL Randomized Controlled Trial (RCT).
Materials and methods: IMPERIAL RCT is a prospective, randomized (2:1), multicenter study of patients with symptomatic femoropopliteal artery lesions (length 30-140 mm, Rutherford category 2-4) treated with the Eluvia paclitaxel-eluting nitinol stent or the Zilver PTX paclitaxel-coated stent. Two-year follow-up included patency, safety, and mortality assessments and core laboratory-reviewed B-mode ultrasound imaging to screen for hypoechogenic halo in the stented segment, and assess blood flow.
Results: At 24 months, all-cause mortality was 7.1% (21/295) for Eluvia and 8.3% (12/145) for Zilver PTX (P = 0.6649). The clinically driven target lesion revascularization rate was significantly less for patients treated with Eluvia vs Zilver PTX (12.7% vs 20.1%; P = 0.0495). The Kaplan-Meier estimate of primary patency at 24 months was 83.0% for Eluvia and 77.1% for Zilver PTX (log rank P = 0.1008). Transverse ultrasound imaging was implemented during the 24-month follow-up window and was evaluable for 27.5% (128/465) of patients. Hypoechogenic halo prevalence rates did not differ significantly between Eluvia and Zilver PTX study arms (33.7% [29/86] vs 21.4% [9/42]; P = 0.153). In no case was flow documented within the halo; no adverse events were associated with these ultrasound findings.
Conclusion: Two-year follow-up suggests a sustained advantage for Eluvia for avoiding target lesion revascularization. Initial hypoechogenic halo assessment showed no difference in prevalence between the study arms, no flow within the halo, and no associated adverse events.
Clinical trial registration: clinicaltrials.gov identifier NCT02574481. Date of registration: October 14, 2015.
Level of evidence: Level 1; randomized controlled trial.
Keywords: Drug-eluting stent; Paclitaxel; Peripheral arterial disease; Superficial femoral artery; Vascular patency.